Although scholars have examined the ethnology, natural history, and geography surrounding the Lewis and Clark Expedition, in the ten expedition reaches Jengo studied, no equivalent earth sciences work exists. Still, multiple scholars questioned the quality, quantity, and accuracy of Lewis and Clark's geological and mineralogical observations, as well as their impact on further scientific inquiry, leading Jengo to scrutinize expedition journals, read hundreds of complex academic geological reports, and utilize rafts, canoes, kayaks, bikes, and hiking trails to visit numerous locations along the route. His extensive research affirms the accuracy and thoroughness of the captains' earth science and geological notations, and he now believes those stinging indictments and misinterpretations are unfair. His new book offers a detailed and accessible presentation of Lewis and Clark Trail geology, delving deep into the geological formations, geomorphic features, and past geological upheavals and catastrophic events, paying attention to the science as it existed in the early 1800s and bringing to light several long-forgotten pioneering geologists. He explores related topics such as native American pictographs, as well as some specific references to art and geological features. Finally, he traces the fate of the rock, mineral, and fossil specimens, even traveling to collection repositories in Philadelphia and Paris.